H8SLASH3003 datasheet(486/715 Pages) RENESAS

486 / 715 page

13.3.4 Synchronous Operation

In synchronous mode, the SCI transmits and receives data in synchronization with clock pulses.

This mode is suitable for high-speed serial communication.

The SCI transmitter and receiver share the same clock but are otherwise independent, so full

duplex communication is possible. The transmitter and receiver are also double buffered, so

continuous transmitting or receiving is possible by reading or writing data while transmitting or

receiving is in progress.

Figure 13-14 shows the general format in synchronous serial communication.

Figure 13-14 Data Format in Synchronous Communication

In synchronous serial communication, each data bit is placed on the communication line from one

falling edge of the serial clock to the next. Data is guaranteed valid at the rise of the serial clock.

In each character, the serial data bits are transmitted in order from LSB (first) to MSB (last). After

output of the MSB, the communication line remains in the state of the MSB. In synchronous mode

the SCI receives data by synchronizing with the rise of the serial clock.

Communication Format: The data length is fixed at 8 bits. No parity bit or multiprocessor bit

can be added.

Clock: An internal clock generated by the on-chip baud rate generator or an external clock input

from the SCK pin can be selected by clearing or setting the CKE1 bit in SCR. See table 13-9.

When the SCI operates on an internal clock, it outputs the clock signal at the SCK pin. Eight clock

pulses are output per transmitted or received character. When the SCI is not transmitting or

receiving, the clock signal remains in the high state. When the SCI is only receiving, it receives in

units of two characters, so it outputs 16 clock pulses. To receive in units of one character, an

external clock source must be selected.

Serial clock

Serial data

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

LSB

MSB

Don’t care

One unit (character or frame) of serial data

Transfer direction

Note:

High except in continuous transmitting or receiving

468

H8/3003 数据表(PDF) 486 Page - Renesas Technology Corp

H8/3003 数据表(HTML) 486 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载